There is known an image forming apparatus in which image forming units for different colors are arranged side by side at locations facing an intermediate transfer belt and which is configured to form a multicolor image by superposing toner images of different colors on the intermediate transfer belt and then transfer the multicolor image to a recording paper sheet with a secondary transfer roller to form an image on the recording paper sheet. This image forming apparatus is provided with a cleaning section for electrically attracting residual toner remaining on the outer peripheral surface of the intermediate transfer belt after the transfer of the multicolor image to the recording paper sheet to collect the residual toner.
However, because electrified charges on the residual toner are not uniform, it may be difficult to sufficiently collect the residual toner using only the aforementioned cleaning section. As a solution to this, there is known a technique for subjecting the residual toner to a pretreatment prior to the collection of the residual toner in the cleaning section. Patent Literature 1 discloses a technique for providing a grounded pretreatment member upstream of a cleaning section in a direction of travel of an intermediate transfer belt to adjust the amount of electrified charges on residual toner and thus increasing the collectability of the residual toner in the cleaning section.